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Detection of Earth-like Civilizations in Space Now Possible

Posted by Zonk on Tue Jan 09, 2007 11:20 AM
from the in-spaaaaaaace dept.
Space Communications Science
Mr. McGibby writes "Astronomers have come up with an improved method of looking for extraterrestrial life with an Earth-like civilization. Theorist Avi Loeb proposes to use instruments like the Low Frequency Demonstrator (LFD) of the Mileura Wide-Field Array (MWA), an Australian facility for radio astronomy currently under construction. The array could (theoretically) detect civilizations broadcasting in the same frequencies as our own society. From the article: 'Loeb and Zaldarriaga calculate that by staring at the sky for a month, the MWA-LFD could detect Earth-like radio signals from a distance of up to 30 light-years, which would encompass approximately 1,000 stars. More powerful broadcasts could be detected to even greater distances. Future observatories like the Square Kilometer Array could detect Earth-like broadcasts from 10 times farther away, which would encompass 100 million stars. ' The original paper describes the details."
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  • Knowing Your Neighbours (Score:5, Interesting)

    by Renegade Lisp (315687) * on Tuesday January 09 2007, @11:21AM (#17523410)

    I think this is a great project. But step back for a moment and think what it means: If there was an earth-like civilization even very close to us, say, at Alpha Centauri, we've had no chance of detecting their stray radiation up until now. And with this new program, it's only within 30 light years that we might be successful. That's really our very, very close vicinity.

    This, I think, puts the fact in perspective that SETI@home hasn't found any signal yet, even after years of listening. They would only be able to detect very powerful transmissions, much more powerful than anything our own civilization could produce.

    The fact that we haven't found any artificial signals from space yet doesn't mean there's nobody out there.

    • The fact that we haven't found any artificial signals from space yet doesn't mean there's nobody out there.

      And to quote Carl Sagan, "Absence of evidence is not evidence of absence."

      • Re:Knowing Your Neighbours (Score:5, Interesting)

        by zippthorne (748122) on Tuesday January 09 2007, @11:55AM (#17523908) Journal
        Ridiculous. It depends on just how much evidence you don't have. For instance, there's very little evidence of the existence of Yeti despite some rather concerted efforts to find anything at all. In fact, there is no evidence at all. Yet mountain lions are easy to find evidence of. Therefore yeti are far less likely to exist than mountain lions.

        Absence of evidence is prima facie evidence of absence.

        The question is, does your lack of evidence result from failing to look or from nothing turning up despite exhaustive searching?

        • Re:Knowing Your Neighbours (Score:5, Insightful)

          by Gulthek (12570) on Tuesday January 09 2007, @12:14PM (#17524188) Homepage Journal
          That depends on how you are searching. Searching for your keys in a cluttered room with the lights off is going to be difficult, and you may look for quite some time without being able to conclude that the absence of evidence is evidence of the keys' absence.

          • Re:Knowing Your Neighbours (Score:4, Funny)

            by mysticgoat (582871) on Tuesday January 09 2007, @01:38PM (#17525392) Journal

            "What are you doing?"

            "Looking for my keys. I dropped them somewhere between the house and the car."

            "But then why are you looking here? This isn't between the house and your car."

            "Well, because its too dark to see them over there. I'm under the street light here. So if they somehow bounced this way, I just might be able to find them."

            And so goes the SETI research, up until now at least.

        • Re: (Score:3, Insightful)

          by div_2n (525075)
          Your assertion is just wrong. Human beings are indirect proof of the possibility of intelligent life elsewhere. The fact that we haven't found/been given/detected evidence is immaterial.

          Regardless, you are attempting a negative proof or proof of impossibility. This is a logical fallacy. Interestingly, it works both ways. You can't prove a Yeti doesn't exist or that life (intelligent or otherwise) exists on other planets because you don't have evidence and vice versa. People can't prove either exist for lack

          • Re:Knowing Your Neighbours (Score:5, Insightful)

            by exp(pi*sqrt(163)) (613870) on Tuesday January 09 2007, @12:52PM (#17524794) Journal
            You are confused about the meaning of the word 'evidence'. When you obtain evidence of X you shift your estimate of the probability of X upwards. That's what 'evidence' means. You need to get this distinction.

            You say "you are attempting a negative proof or proof of impossibility" which demonstrates you didn't actually read or understand the parent post which stated, quite clearly, "Absence of evidence is prima facie evidence of absence.", not "Absence of evidence is prima facie proof of absence". Until you sort out the difference between proof and evidence the rest of what you say is moot.

              • Dictionaries are hopeless for providing definitions in even a slightly technical domain. Almost every definition of "evidence" in a dictionary is hung up on the notion of proof, probably because of the common legal use of the word. For this reason dictionary definitions tend to define 'evidence' in terms of 'proof'. But read just about any scientific literature - you will find many uses of the word 'evidence' but very few uses of the word 'proof'. In fact, 'proof' is something of a taboo word in scientific
        • For a slightly more formal treatment see here [blogspot.com]. Sagan was talking out of his ass when he said that and there's nothing more annoying than people who keep quoting it.

        • Re:Knowing Your Neighbours (Score:5, Interesting)

          by peragrin (659227) on Tuesday January 09 2007, @12:47PM (#17524726)
          I forgot the name of the species of fish but scientists thought it to be extinct. For years the evidence pointed to the fact that the particular fish no longer existed, yet one day a fisherman caught one.

          A lack of evidence either way doesn't mean it doesn't exist. There are numerous example of animals that hide first. The possum "plays" dead. An animal intelligent enough to hide from other species isn't unheard of. Given the right locations on earth, two mountainous and relatively uninhabited area's. It is possible a yeti, and big foot exist.

          of course that being said I won't believe it until I see it, but that doesn't mean it's impossible, just improbable. That's a huge difference.

          • Re: (Score:3, Informative)

            by Reducer2001 (197985)
            Coelacanth [wikipedia.org]

          • Re: (Score:3, Informative)

            by cnettel (836611)
            Coelacanths. A specific species within a large group was found in 1938. Established science had assumed them to be extinct, simply because the last fossil records were 70 million years old or so. No European had gone out of their way to really look for it, and when a reward was announced and the news of it trickled out, it was discovered that it was known to exist in the seas around the Comoros.

          • You are exactly right and I can't believe all of the people who are just so wrong on this.

            It's very much like this.

            Joe: All swans are white.
            Jill: What evidence do you have?
            Joe: I saw a swan and it was white, hence, all swans are white.

            Any of us looking at this would see that Joe's assertion is unproven. The absence of a non-white swan in Joe's search is not proof that non-white swans are absent, if you'll pardon my tortured language for illustrations's sake. Now:

            Joe: All swans are white.
            Jill:

      • Re:Knowing Your Neighbours (Score:4, Insightful)

        by rleibman (622895) on Tuesday January 09 2007, @12:48PM (#17524742) Homepage
        And to quote Carl Sagan, "Absence of evidence is not evidence of absence."

        I'll take your quote and raise: "Extraordinary claims require extraordinary evidence"

    • Re:Knowing Your Neighbours (Score:5, Insightful)

      by Minimum_Wage (1003821) on Tuesday January 09 2007, @11:33AM (#17523600)
      The flaw with all these searches is that it assumes that any nearby civilizations are exactly at the same level of development as humanity. Isn't high-power broadcast radio actually declining on Earth right now in favor of cable, fiber, and low power systems like the small satellite DBS dishes? If an alien civilization isn't in the same +/- 50 year technological window as we are, we'll probably never hear them even if they are next door. Still, if you don't look you'll never be sure...

      • Re:Knowing Your Neighbours (Score:4, Informative)

        by silentounce (1004459) on Tuesday January 09 2007, @12:16PM (#17524220) Homepage
        This argument has come up several times. If you RTFA then you will see this: "On Earth, military radars are the most powerful broadcast sources, followed by television and FM radio. If similar broadcast sources exist on other planets, facilities like MWA-LFD might detect them."

        TV and communication media are not the only sources of radio waves. It would stand to reason that most civilizations that develop flight will eventually develop radar. Radar is very simple and reliable. Yeah, I know that there are stealth technologies, but commercial jetliners aren't using them. We'll probably be using radar for a very long time. Plus, radio is our current means of communicating with our spacecraft(isn't it? I may be wrong). If the society is space faring, and they have a well-developed space program, that may be a large source of radio waves that won't even have to escape an atmosphere.

        • Re:Knowing Your Neighbours (Score:5, Funny)

          by multipart/mixed (163409) on Tuesday January 09 2007, @12:42PM (#17524634)
          > Plus, radio is our current means of communicating with our spacecraft(isn't it? I may be wrong).

          No, we use quantum entanglement for long-distance communication, and gravity waves for short-distance (say, under 5 light years). Radio is too slow for the distances involved.

          • Re: (Score:3, Interesting)

            by JavaLord (680960)
            that assumes they want to find us, or even find us worthy of contact. They may have found us already, reported back to their homeworld, and decided we're not worth their time to look at, maybe we're too far, (could take them a long time to get here) could be we don't (didn't) have a sufficiently advanced civlization. And heck if the probe took 250,000 years to find us, who's to say that the originating civilization hasn't given up, or disappeared, died out, sun went nova? who knows. and if it takes 500,000

            • Re: (Score:3, Interesting)

              by HiThere (15173)
              Well, the lifespan has to be approximately right. It could be longer, but much shorter and there isn't that much reason to evolve intelligence. Mind you, if they run their bodies hotter or colder this is subject to variation. (Chemical reaction speed being thermally determined.)

              If their lifespan is longer, one needs to wonder what part of their lifespan is longer? Childhood or adult? It would make a big difference as to their nature. Long childhood would lead to more flexible thinkers. Long adult wou

        • Re: (Score:3, Insightful)

          by Mozk (844858)
          Still, never hurts to check...

          It does hurt when the funding, research, and effort could be put to better uses. We ought to work on our needs such as learning about our own planet (there's so much that we don't know), and how our species is going to survive, since at the current rate, survival could become a problem fairly soon. What we shouldn't be worrying about is philosophical questions like if there is life on other planets or the infamous "are we alone?" Sure, finding life on other planets can give imm

    • What does "Earth like" mean? (Score:4, Interesting)

      by soft_guy (534437) on Tuesday January 09 2007, @11:35AM (#17523632)
      Would this method have detected our civilization in the 1800s? 1910? 1930? 1950?

      What exactly is it detecting? FM radio? Television? Radar? Emissions from cars? Would it detect a working telegraph?

          • Re:Knowing Your Neighbours (Score:5, Funny)

            by egyptiankarim (765774) on Tuesday January 09 2007, @02:57PM (#17527058) Homepage
            Universes Worst AIM Conversation Ever... EarthDudez: Hey! Waz up? [30 years later] GrayGuys: Nothing much... u? [30 years later] EarthDudez: brb [400 years later] EarthDudez: back! [30 years later] GrayGuys: your moms back. [30 years later] EarthDudez: lolz. dude you're so GrAY! [30 years later] GrayGuys: lol

  • "Earth-like" civilizations? (Score:5, Funny)

    by TheWoozle (984500) on Tuesday January 09 2007, @11:26AM (#17523474)
    Great...

    So we're going to pick up an alien version of "The View"?

  • any physicists out there? (Score:5, Funny)

    by Lord Ender (156273) on Tuesday January 09 2007, @11:27AM (#17523486) Homepage
    Could you list any of the current areas of research which may some day allow for information transmission faster than c? Let's keep in reasonable: only mention theories we may be able to explore within the next 1000 years.
    • Isn't there something to do with the spin of an electron, which when you reverse the spin, immediately reverses the spin of some other electron, with no delay? Couldn't you reverse the spin of a bunch of electrons on earth, and have their counterparts match the reversal, 30 light years away. It could be used for exchanging information at faster than light speeds.
      • Isn't there something to do with the spin of an electron, which when you reverse the spin, immediately reverses the spin of some other electron, with no delay? Couldn't you reverse the spin of a bunch of electrons on earth, and have their counterparts match the reversal, 30 light years away. It could be used for exchanging information at faster than light speeds.

        You are thinking of quantum entanglement, aka "spooky action at a distance".

        It cannot be used to transmit information. Think of it this way:

        1. You take two slips of paper, one black and one white, and put them in envelopes.
        2. You randomly select an envelope and mail it to your brother in Poughkeepsie. You keep the other envelope for yourself.
        3. While the envelopes are in transit, nobody has yet observed their contents (i.e. their spins). Yet you know that their contents (their spins) must be opposite because they are an entangled pair.
        4. The envelope travels to Poughkeepsie at the speed of light, or significantly slower in the case of the US Postal Service.
        5. Your brother receives and opens his envelope. He observes that his slip of paper is black. The uncertainty collapses: he now instantly knows that your slip of paper is white.

        Notice that you cannot send actual information by this route. The uncertainty of "which slip of paper is in my envelope?" collapses instantaneously, but it collapses into a random choice. Neither of you could know in advance which color you would find in your envelope.

        This illustration changes slightly when executed at the quantum level: while the envelopes were in transit, both slips of paper were actually grey... though some might insist that they were both all possible colors, until they were finally observed.

          • Re: (Score:3, Informative)

            by TopherC (412335)
            The history of this feature of quantum mechanics is fascinating!

            Einstein, Podolski, and Rosen proposed this as a thought-experiment to show that the hocus-pocus in quantum mechanics was silly, and that really the envelope always "knew" what color paper was inside it. They used this setup, together with the understanding that nothing could travel faster than light, to show that the envelopes always had definite papers inside just like you'd imagine, which also means that quantum mechanics is an incomplete t

    • Re: (Score:3, Informative)

      by MindStalker (22827)
      Only if you redefine c. Theoretically c can be increased in some special situations such as extremely high gravity fields and other things. But in general traveling faster than c reverses cause and effect, which can't happen. Though one may eventually figure out how to jump from one side of the universe it wouldn't be traveling per say.
  • How can we be sure that extraterrestrials (if there are any) are broadcasting radio waves? What makes us think they would be communicating in an 'Earth-like' way?

  • Impossible! (Score:5, Funny)

    by LiquidCoooled (634315) on Tuesday January 09 2007, @11:28AM (#17523504) Homepage Journal
    The Recording Industry Galactic Alliance (RIGA) mandated that no radio signals shall leave the atmosphere of any planet.

    The respective governments all attempted to stop this legistation getting in but the RIGA had bigger guns!
  • 30 light-years, which would encompass approximately 1,000 stars.

    I guess it depends on how abundant life is, but this doesn't seem like it is very far/much in the grand scheme of things.

    Even if an advanced civilization is out there, what makes us think they would be using radio? It's possible, but I could see FM radio being obsolete 100 years from now. I know the article mentions radar too, but it seems like a lot to assume...that advance life evolved, and is around the same time in techonological p

    • Re:Hmm. (Score:5, Insightful)

      by silentounce (1004459) on Tuesday January 09 2007, @11:39AM (#17523670) Homepage
      "Given the massive distances between stars, astronomical mass extinction theories, and the time evolution takes, aren't the odds of two technically advanced civilizations being around at the same time...umm astronomical? :)"
       
      The true probabilities are not known. We don't know how common life is. We don't know how often a mass extinction of life occurs. We don't know how long evolution takes except for on our one world. We don't have enough data to accurately predict whether or not life is rare or common in the universe. Another perspective could be that it is in fact more likely that advanced civilizations would be around at the same time if the universe has a consistant timeline. If the way that life-harboring star systems form, the way that life itself forms, and the way that intelligent life evolves is analogous across the universe then this may be the Golden Age of intelligent life throughout our galaxy.

    • Re: (Score:3, Interesting)

      by MindStalker (22827)
      Exactly, though its a given that if an alien civilization more advanced than use WANTED to be found they would use multiple technologies radio being one of those. Radio would most likely be a baseline technology that any advanced civilization capable of interstellar communication would have already reached.

  • Obligatory (Score:5, Funny)

    by inviolet (797804) <pineminder@yaho[ ]om ['o.c' in gap]> on Tuesday January 09 2007, @11:29AM (#17523520) Journal

    And I, for one, welcome our new nearby, low-frequency-emitting overlords.

    And I would like to remind them that as a net.geek, I could be useful in rounding up others, to toil in their oneline goldfarms.

  • Let's hope they're not like us (Score:4, Funny)

    by orson_of_fort_worth (871181) on Tuesday January 09 2007, @11:29AM (#17523528)
    The signals we'd pick up from a civilization similar to ours would be viagra spam and Saved by the Bell reruns. So disappointing it might set back space exploration by centuries.

  • Window of opportunity (Score:3, Insightful)

    by TubeSteak (669689) on Tuesday January 09 2007, @11:30AM (#17523536) Journal
    How long do "earth like" civilizations put out RF energy that is detectable from space?
    How long will we keep doing it?

    Searching for XYZ years worth of RF in a bubble 60 light years across doesn't strike me as very promising.

  • Not a big area (Score:5, Interesting)

    by Orange Crush (934731) on Tuesday January 09 2007, @11:35AM (#17523630)

    30 or even 300 LY is tiny on a galactic scale. Then again, anybody who's more than 30 ly away won't be able to have a meaningful conversation with us over the course of a single researcher's lifetime . . . unless of course they're kind enough to send instructions on how to communicate FTL.

    Speaking of FTL communications . . . maybe civilizations only use radio for a relatively short time in their development. Present understanding of physics pretty much rules out FTL communications, but there could always be some exotic aspect of our universe we haven't discovered yet that would allow it and we'll finally be able to log in to the giant IRC server of the universe.

    • Re:Not a big area (Score:5, Interesting)

      by David_Shultz (750615) on Tuesday January 09 2007, @12:17PM (#17524244)
      anybody who's more than 30 ly away won't be able to have a meaningful conversation with us over the course of a single researcher's lifetime

      Are you joking? Do you not think it would be meaningful just to receive the message "hello"? this would be one of the most important moments in the history of humankind (not to mention alienkind). A long conversation isn't needed for this to be meaningful. Heck, no conversation is required -we just want to find someone else out there.

  • my question is... (Score:4, Funny)

    by jimstapleton (999106) on Tuesday January 09 2007, @11:47AM (#17523790) Journal
    Do we have the tech to set up a powerful and focused transmitter that would be recievable by standard radio devices on a planet (if we find one) that far away?

    I can see it now.

    "Citizens of Earth, the Xibian Communication Commision (XCC) is ordering a Cease and Desist of projection of signal on channel 88.6. Failure to follow this within the standard grace period of 1 Xibian day will result in fines of 100 Toriks per Xibian Day. Given that you are 50 Xibian years distant (as light travels), at 250 Xibian days per year... It really sucks to be you."

  • Fiber to the Home. (Score:5, Interesting)

    by crhylove (205956) <rhy@leperkhanz.com> on Tuesday January 09 2007, @11:51AM (#17523834) Homepage Journal
    Unless alien civilizations are just as beholden to corporate interests and backward technology as we are (which I doubt, and if it is the case why should we bother communicating with their ignorant asses anyway?), I would assume their civilization has fiber to the home, and I doubt their wireless controllers, cell phones, and remote controls are going to have a signal that gets off the planet at all.

    If we were REALLY interested in contacting alien civilizations, we would make our own much more attractive first. I doubt any alien civilization is going to be interested in sharing technology with a planet of retarded monkeys that give morons like Bush who openly admit talking to invisible men in the sky nuclear weapons.

    As a matter of fact, I can't imagine any advanced civilization bothering with the kooks who live here and believe in such ludicrous stone age fantasies. Particularly kooks with nuclear weapons and who engage in water-boarding.

    I'm so ashamed of our whole species I can't even begin to imagine why *I* bother interacting with them, much less some aliens who weren't so unlucky as to be born in this idiotic power-structure of ignorance.

    rhY

    • Re:Fiber to the Home. (Score:4, Insightful)

      by cowscows (103644) on Tuesday January 09 2007, @12:23PM (#17524360) Journal
      Thank you, those are some very useful comments. I'm sure that all the astronomers out there, having read your post, are preparing their resignations, and will instead focus their time on solving all of the world's troubles. Thank you again, for bringing these issues to our attention.

  • Well, what are we looking for...? (Score:3, Insightful)

    by MetaPhyzx (212830) on Tuesday January 09 2007, @11:51AM (#17523840)
    Essentially, we're looking for someone "out there" that thinks/acts/interacts with their world the way we did with ours. It's almost identical to looking for carbon based life forms like us, on other worlds (Mars as an example). I understand that it's easier to start looking for what you already know, but with the variance of life and how we interact/communicate just on this planet, maybe we can think a bit more outside the box?

  • intelligent life on earth? (Score:3, Interesting)

    by peter303 (12292) on Tuesday January 09 2007, @12:03PM (#17524018)
    From the way be behave, I wonder.
    Remember Star Trek IV when the aliens though just the marine mammals were intelligent.

  • Whoa, there... (Score:5, Funny)

    by Rob T Firefly (844560) on Tuesday January 09 2007, @12:10PM (#17524118) Homepage Journal
    improved method of looking for extraterrestrial life with an Earth-like civilization
    Do we really want to find something Earth-like? I for one would rather find someone who's got it right. We need a wise older sibling, not an equally dysfunctional twin.

    I could just imagine the space phonecalls..

    EARTH: Hey, guys. How's it going?"
    ALIENS: Well, our environment is crapping itself, we're all trying to kill each other, and we still won't grant marriages to every couple who wants one.
    EARTH: Yeah, same here. Any, you know, wise alien tips for us?
    ALIENS: Well... have you invented Reality TV yet?
    EARTH: Yep, doesn't seem to have helped much.
    ALIENS: Have you, I dunno, tried invading someplace oil-rich?
    EARTH: Done that, lots of times.
    ALIENS: How about starting arguments about the origins of your own species?
    EARTH: Oh hell, don't get me started on that can of worms buddy.
    ALIENS: Well, try inventing a couple of new incompatible game consoles...

  • At last ! (Score:4, Funny)

    by Salsaman (141471) on Tuesday January 09 2007, @12:13PM (#17524180) Homepage
    At last we will be able to receive "Single Female Lawyer" !

  • Technology trends from our own planet (Score:3, Informative)

    by east coast (590680) on Tuesday January 09 2007, @12:22PM (#17524344)
    More powerful broadcasts could be detected to even greater distances [over 30 LYs].

    Maybe I'm wrong but I would think that as a civilization becomes more advanced that the power of their broadcasts would decrees and the signals would become more focused. Would it be easier to detect a signal from 20 years ago from a few light years away than what it would be to detect today's signals? If so I think we'd be looking at a small window of opportunity to detect another civilization.

    This isn't to say that widening the spectrum of the search is a bad thing but I'm just trying to get my head around how useful this might really be.

  • Optical SETI is the way to go (Score:3, Interesting)

    by TheSync (5291) * on Tuesday January 09 2007, @01:05PM (#17525012) Homepage Journal
    Optical SETI with intense nanosecond light pulses is the way to go, forget radio!

    1. Visible light-emitting and detecting devices are smaller and lighter than microwave or radio-emitting devices.

    2. Visible light-emitting devices produce higher bandwidths and can consequently send information much faster.

    3. Interference from natural sources of microwaves is more common than from visible sources.

    4. Naturally occurring nanosecond pulses of light are mostly likely nonexistent.

    5. Existing lasers can produce nanosecond pulses that can outshine a star by 30 times.

    http://observatory.princeton.edu/oseti/oseti.html [princeton.edu]

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